1. The Field of the Invention
This invention relates to tuning apparatus and more particularly to that class which automatically adjusts the pitch of the instrument to be tuned in accordance with a set of provided frequency standards.
2. Description of the Prior Art
The prior art abounds with apparatus utilized in tuning musical instruments. U.S. Pat. No. 2,761,994 issued on Sept. 1, 1956 to J. W. Quitmeyer teaches a stroboscopic disc utilized as a frequency standard and providing indicia means which indicates the correct tuning of any note in the chromatic tempered scale of notes, employing a microphone which receives the sound of the played note which is then compared to the standard pitch by illuminating a lamp casting light upon the disc.
U.S. Pat. No. 3,509,454 issued on Apr. 28, 1970 to D. Gossel discloses an apparatus for tuning musical instruments in which the output of a variable frequency generator is compared with a signal adduced from the musical instrument by utilizing a digital divider to produce two frequencies, differing by one musical half-tone. After comparison in a phase sensitive comparator, the frequency differences are optically displayed.
U.S. Pat. No. 3,631,756 issued on Jan. 4, 1972 to R. C. Mackworth-Young pertains to an apparatus for tuning a musical instrument comprising a generator of electric oscillations of reference frequency including an array of tuning forks which can be brought, in succession, into register with a driving coil for maintaining the adjacent tuning fork in oscillation. A pick-up coil provides a signal dependent on vibrations of the said tuning fork. The signal is amplified by an amplifier and fed on the one hand to the driving coil and on the other hand to a frequency comparator with a "magic Eye". A microphone, for picking up oscillations from a vibratory element of the musical instrument to be tuned, is connected through an amplifier to the frequency comparator.
All of the aforementioned patents suffer the common deficiency of requiring manual trial and error techniques to obtain the proper output pitch from the instrument to be tuned, even though the need to use one's ability to audibly compare the pitch from a frequency standard, such as a tuning fork, to the pitch produced by the musical instrument, the utility of such devices are limited for use by operating personnel possessing the manual dexterity and patience to adjust the pitch of the musical instrument upwards and downwards until the visual indicator provides him with information that the correct pitch has been achieved.